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Ask Well: Whiter Teeth

By Catherine Saint Louis March 20, 2015 5:45 amMarch 20, 2015 5:45 am

Photo

Credit Getty Images

Q

What is the healthiest and most effective way to whiten your teeth?

Reader Question • 1494 votes

A

There is no shortage of ways to treat tooth discoloration: strips, rinses, brush-on gels and toothpastes sold at pharmacies; bleaching treatments at the dentist; trays bought at the dentist’s office for home use. The bottom line is all these methods work, but some require patience, and others a tolerance for painful sensitivity. And results will be only temporary.

Higher concentrations of hydrogen peroxide, a bleaching agent used in many whiteners, can be delivered in a dentist’s office, so those procedures tend to be quicker than drugstore aids. But tooth sensitivity and gum irritation can occur, and the higher the concentration of the peroxide used, the more severe these side effects are likely to be.

More aggressive treatment isn’t necessarily more efficacious, either. A randomized trial of 90 patients found that use of a home bleaching tray with a 10 percent carbamide peroxide gel for two weeks offered the same degree of whitening as two in-office sessions using 35 percent hydrogen peroxide with light, which some dentists use because it supposedly activates bleaching agents.

Some dentists also use heat or even lasers to activate bleaching agents. But a 2007 systematic review of evidence in the journal Dental Materials found no added benefit from heat, light or lasers and suggested these methods “may have an adverse effect on pulpal tissue,” the soft material in the tooth’s center. If pulp is injured, it may require a root canal to fix.

Heat and hot lights can also have a dehydrating effect on teeth, which can make them look whiter. It can take weeks for the teeth to rehydrate and slightly darken.

Dr. Ronald D. Perry, the director of the Gavel Center for Restorative Research at Tufts University School of Dental Medicine, said that over all, “the light doesn’t really do anything, but the marketing behind it is so powerful.”

Before any bleaching, even when it’s done at home, a dentist should check fillings and crowns, because, Dr. Perry said, applying peroxide to a restoration that is no longer perfectly sealed will be very sensitive.

In a 2014 review of tooth whitening studies, Clifton Carey, a professor at the University of Colorado School of Dental Medicine, warned that fillings that are designed to match the tooth’s color might get more yellow after even drugstore whiteners. Or, if teeth get whiter, and a filling doesn’t, it might stand out.

Not all staining is alike. It can be caused by external factors like wine, coffee, cola and smoking, and bleaching is effective against these. Aging is another culprit, as enamel wears down and the yellower dentin that lies beneath becomes visible. Bleaching does work on older teeth, too.

Unfortunately, it’s tricky to say how long the results of tooth whitening will last. A nightly merlot drinker with freshly lightened teeth may re-stain them in a month or two.